Forty years ago, we chose this day in April to express our concern for the state of the planet. At the time, people were worried about air pollution, water pollution and the threat that the “population explosion” was going to overrun the planet’s resources. Where energy was concerned, we worried instead about fouling the air with fossil fuel pollution, drowning precious landscapes by building Western dams, and possible oil scarcity.

So we’ve made a lot of progress. We’ve certainly reduced air pollution. Our cars are about 98 percent cleaner in their overall emissions than they were 30 years ago. The air in our cities is also much cleaner – for example, sulfur dioxide emissions have cut in half since the 1970’s. Our rivers are no longer industrial sewers as we have improved management of storm water runoff and enhanced our water treatment capabilities. Municipal waste is being treated, fish populations are bouncing back and we are making real progress restoring our waterways. But we can all agree that there is more to be done.

There’s one more thing worth remembering about the first Earth Day and that is that, at the time, the Sierra Club and other environmental organizations were supporting nuclear power. In fact, nuclear energy was regarded as a savior to our environmental dilemmas. It cleaned the air of pollution and didn’t take up a great deal of space. You didn’t have to drown all of Glen Canyon to produce 1,000 megawatts of electricity. With nuclear power, you could do it on one square mile. But that support from the environmental community quickly disappeared and we haven’t started a new nuclear power plant in 30 years – mostly as a result of the fear perpetuated from the incidents at Three Mile Island and Chernobyl.

Today a lot of environmentalists are starting to rethink nuclear energy. President Obama himself has endorsed it, proposing an expansion of the loan guarantee program and making the first award to the Vogtle Plant in Georgia. Secretary of Energy Steven Chu wrote recently in The Wall Street Journal about developing a new generation of mini-reactors in this country.

Now, I know a lot of environmentalists feel betrayed by this. “We laid nuclear to rest twenty-five years ago with Three Mile Island and Chernobyl,” they say. “Why is it now crawling out of its grave?” For many people, nuclear is the exact opposite of “green.” They say it’s big, it’s industrial, it’s bureaucratic, it’s expensive, it involves handling dangerous materials, and it’s not soft and nice and sustainable like those energy technologies we admire.

So why would anyone consider nuclear green? The main thing is its tremendous energy density. The Nature Conservancy took note of this last August in their paper on “Energy Sprawl.” The authors looked at the amount of space required to produce energy from the various technologies – something no one had ever done before. They came up with some remarkable findings.

Nuclear turns out to be the gold standard. You can produce a million megawatt-hours of electricity a year – that’s the standard they chose – from a nuclear reactor sitting on one square mile. That’s enough electricity to power 90,000 homes. A coal-powered plant absorbs four square miles when you count all the land required for mining and extraction. A solar thermal plant, where they use big mirrors to heat a fluid, takes six square miles. Natural gas takes seven square miles and petroleum takes 17 – once again counting the land needed for drilling and refining. Photovoltaic cells that turn sunlight directly into electricity take 14 square miles and wind is even more diluted, taking 28 square miles to produce the same amount of electricity.

These are some pretty big numbers. When people say “We want to get our energy from wind,” they tend to think of a nice windmill or two waving gently on the horizon. “Maybe I’ll even put one in my back yard,” some might think. They don’t realize those nice, friendly windmills are now up to 50 stories high and can have blades with a diameter the length of a football field. They are loud and can make a low-decibel noise heard from miles away and can also kill a lot of birds – up to eight per windmill per year according to the American Bird Conservancy.

It’s the same for photovoltaic solar panels. We would need to cover fifty square miles of desert in order to equal the output of one nuclear plant. And then there will be hundreds of miles of transmission lines to bring this electricity from remote areas where it is generated to the cities where it is needed. At some point this stops being picturesque and begins to look like what good environmentalists and conservationists have always fought against – the destruction of natural landscapes by industrial civilization.

These are things we can’t just brush aside. We don’t want to end up destroying the environment in the name of saving the environment. Just as there is no such thing as a free lunch in economics, in nature there is no such thing as free energy. Anything we do is going to affect the environment. No matter how “green” and “sustainable” we may want some form of energy to be, it’s going to have an impact. The real question is which form of energy has the potential to have the smallest impact? I think the answer is “nuclear power.”

Stephen, when people are freezing to death in their homes
during a severe cold snap due to an extended power failure you can console them
with the knowledge that the stationary windmills all around then are
technically available.

Jacobson’s paper makes this claim;

“It was found that an average of 33% and a maximum of 47% of
yearly averaged wind power from interconnected farms can be used as reliable,
baseload electric power….”

This is what the review comment is about, not windmill
availability.

Jacobson wrote; “Nevertheless, because coal plants were shut
down for scheduled maintenance 6.5% of the year and unscheduled maintenance or
forced outage for another 6% of the year on average in the United States from
2000 to 2004, coal energy from a given plant is guaranteed only 87.5% of the
year, with a typical range of 79%–92% (North American Electric Reliability
Council 2005; Giebel 2000).”

Note that I used the same database he uses to show that his
conclusion is not valid. The reliability of fossil fuel supply is high, so the
reliability of fossil based electricity is nearly equal to plant reliability.

Jacobson wrote; “"Firm capacity" is the fraction
of installed wind capacity that is online at the same probability as that of a
coal-fired power plant.”

This is where the authors have redefined reliability. First
they use the term, “Firm capacity,” and then when they write their conclusion
it is “reliable.”

Imagine that someone invents a cold fusion generator that is
very cheap to mass produce, but can only be operated at rated power for 1 hour
in every 10 hours. The “Firm Capacity” of these units is only 10%, less than
one fourth the 45% Jacobson claims as the “Firm Capacity” of the windfarms.

A utility would buy enough units to cover its highest demand
day, and have a totally reliable grid year round with no backup plants, no
storage and no additional transmission lines required. That is because each
unit can be scheduled well in advance and dispatched as needed. These are the
qualities that give an energy source reliability, and they are not present with
wind farms, even if they are interconnected. “Firm capacity” is not an
indication of, or correlated with, or equivalent to reliability, except at the
end points of 0% and 100%.

Stephen, do you think “Firm Capacity” is a better measure of
reliability than IEEE 762?

Jacobson’s entire paper hangs on the assumption that
“firm capacity” and “reliability” are equivalent and interchangeable, in direct
contradiction of this example, the examples in the comment, common sense and
industry standards.

Maintaining grid reliability is a matter of life and death.

People who try to reduce grid reliability to a word game
reveal more about themselves than they reveal about our energy options.

So, your unanswered questions are;

1… Jockeying fossil plants to load level wind means many
more thermal stress cycles, higher maintenance cost for those plants and higher
emissions. It also reduces thermodynamic efficiency. Where are these costs
included in your academic wind analysis?

2… How much hydro power would we have built if it only
generated power while it rained?

3… Would it be reliable baseload power if we interconnected
those rain only hydro plants? It’s always raining somewhere, right?

4… What would the transmission system for that cost?

5… How much money do you think we should be spending on
R&D to make reliable, clean, safe, dispatchable energy that is cheaper than
burning coal?

6… What is your definition of dispatchable?

7… What is the power industry definition of dispatchable?

8… What is your definition of baseload power?

9… What is the industry definition of baseload power?

10… What does the subsidy for commercial nuclear power (not
military or fusion) add up to in cents per kWh? Reference please.

11… What do the taxes paid on nuclear kWh's add up to in
cents per kWh?

You mentioned the insurance issue again. You still have 14
questions to answer on that issue.

Bill - "Stephen, I see you’re still trying to steer the conversation
away from the important questions related to maintaining a reliable
grid."

Not at all - I am trying to get you to focus on the problem that you have with quoting and IEEE standard, accusing another engineer of not adhering to it and inventing terms when by the terms of the standard that YOU quoted, wind power is just as reliable, under the limited terms of the standard, as fossil fuel generators.

The twenty questions you posted I have no intention of answering as they are not relevant to the original discussion regarding the IEEE standards and wind power. They are a rather pathetic attempt to divert attention away from the fact that you did not seem to have a clear understanding of the relevant terms when you criticised Jacobson in a formal reply.

"You mentioned the insurance issue again. You still have 14
questions to answer on that issue."

Which were also an evasion to cover the gap between your claim that the Price Anderson act is not needed and the unseemly haste to which is was renewed with bi-partisan support when it was in danger of lapsing. A gap that you had no explanation for.

Humans have been building windmills for over 300 years. The latest
designs operate close to theoretical maximum efficiency; there is little room
for improvement.

Power reactors have existed about 50 years. They split about
1 percent of the uranium mined to fuel them and operate at somewhat low
thermodynamic efficiency. They are all hand built on site and no two are
exactly alike. The nuclear power industry is where the car industry was before
the Model T. there is enormous room for improvement. The fact that such a
primitive level of development can compete with mature fossil technology hints
at its potential.

Stephen, I see you’re still trying to steer the conversation
away from the important questions related to maintaining a reliable grid.

1… Jockeying fossil plants to load level wind means many
more thermal stress cycles, higher maintenance cost for those plants and higher
emissions. It also reduces thermodynamic efficiency. Where are these costs
included in your academic wind analysis?

2… How much hydro power would we have built if it only
generated power while it rained?

3… Would it be reliable baseload power if we interconnected
those rain only hydro plants? It’s always raining somewhere, right?

4… What would the transmission system for that cost?

5… How much money do you think we should be spending on
R&D to make reliable, clean, safe, dispatchable energy that is cheaper than
burning coal?

6… What is your definition of dispatchable?

7… What is the power industry definition of dispatchable?

8… What is your definition of baseload power?

9… What is the industry definition of baseload power?

10… What does the subsidy for commercial nuclear power (not
military or fusion) add up to in cents per kWh? Reference please.

11… What do the taxes paid on nuclear kWh's add up to in
cents per kWh?

You mentioned the insurance issue again. You still have 14
questions to answer on that issue.

I also do not understand why you persist in repeating provably false statements; nuclear fission power plants have been producing on-demand power ever since the first ones served as the power plant on board a ship. That first reactor went to sea on January 17, 1955.

The very large plants that certain commercial vendors decided were the way to make fission competitive in the electrical power market are simply a matter of design choices; they do not represent limitations of the basic physical heat source of fission. Fission reactors can change the rate at which they produce heat as quickly as combustion engines can; sometimes they can even do it faster.

I also do not know what planet you come from; operating nuclear power plants in the United States have NEVER received any production credits. The "subsidies" that you point to are imaginary; they do not cost the taxpayers or rate payers any money at all. In fact, selling liability insurance to nuclear power plant owners is a very lucrative business. The fund set up to handle used nuclear fuel in the US has accumulated a balance of tens of billions of dollars, even though a great deal of it has been wasted paying geologists to drill holes into rocks and try to prove their stability for a million years.

Used fuel material is an energy resource, not a waste product. It has tremendous value when treated as such; it should not be considered a liability.

Rod - "Stephen - we
have done that experiment thousands of times with just nuclear. Every
time a US aircraft carrier or submarine gets underway, it becomes an
isolated grid powered solely from nuclear fission."

Please take the hint for the love of whatever god you pray to ....................!!!!!

No it is not, so why did you make the huge rant in the formal reply, that you claim he evades, when it is not about reliability as defined by the IEEE?

No wonder he does not answer it as it is nonsensical by your own admission. So just where are you going here?

"How much money do you think we should be spending on R&D
to make reliable, clean, safe, dispatchable energy that is cheaper than
burning
coal?"

First of all conventional nuclear is not despatchable - it requires either specially modified nuclear power plants or other despatchable fossil fuel power plants to operate. Nuclear also requires massive subsidies in the form of insurance guarantees and waste disposal subsidies quite apart from the production credits that it has received over the years.

My argument is if the truly massive investments in nuclear R&D both civlilian and military spin-offs have STILL failed to make it a viable energy source in it's own right after 50 years of trying maybe it is time to stop flogging the dead horse.

However I do agree that we should be "we should be spending on R&D
to make reliable, clean, safe, dispatchable energy that is cheaper than
burning
coal" and that is geothermal, solar wind and other renewables along with the required interconnections.

How much hydro power would we have built if it only generated
power while it rained? Would it be reliable baseload power if we interconnected
those rain only hydro plants? It’s always raining somewhere, right? What would
the transmission system for that cost?

The fact that you play word games and evade the important
points, like Jacobson avoids the points in my review comment, puts things in
proper perspective.

How much money do you think we should be spending on R&D
to make reliable, clean, safe, dispatchable energy that is cheaper than burning
coal?

Ed - "Perhaps the issue could be advanced by isolating a significant grid and powering it with solar and wind, combined with a smart grid."

Sure Ed and while we are at it we could isolate another area and power it solely from baseload only nuclear and see how that goes.

Stephen - we have done that experiment thousands of times with just nuclear. Every time a US aircraft carrier or submarine gets underway, it becomes an isolated grid powered solely from nuclear fission. I can testify that the power is generally quite reliable. We occasionally turn it off for training and every once in a very great while we have an unplanned outage. Other than that, it works fine, lasts a very long time and is quite responsive to changes in the demand.

Bill - "Stephen, enjoy your word games if you like. Under your system
wind power reliability is equal to windmill reliability times “wind
fuel”
reliability, which is awful."

Its not word games. You were the one that insisted with a formal reply to a peer reviewed paper that Jacobson was not defining reliability in the correct manner according to the IEEE which you seem to take pride in saying that you were the one that held him to this standard.

However it seems that maybe that wind is as reliable under the IEEE definitions. The crux of the matter comes to the definition of a generating unit. As far as I can see the generating unit is contained within the site of the generator and does not include fuel pipelines outside it.

Stephen, enjoy your word games if you like. Under your system
wind power reliability is equal to windmill reliability times “wind fuel”
reliability, which is awful.

It is not predictable or dispatchable. It does not add
stability to the grid, it absorbs stability from the grid. It requires a
massive new transmission system. Good luck condemning all the land needed for
transmission lines. People will be outraged when they see those big power lines
going up. It will take much longer to complete the grid than building
conventional nuclear plants.

You demanded fact based reports; I gave you one that shows
emissions go up when fossil plants are forced to load level for windpower. No
comment from you. Steam turbines have massive shafts, blades and cases made of
steel several inches thick in some places. Jockeying those plants to load level
wind means many more thermal stress cycles and higher maintenance cost for
those plants. Where are these costs included in your academic wind analysis?

The reality is that Denmark has been pushing wind hard since
1979, at enormous cost, to achieve 150 watts of wind per person, half of which
they export because they cannot use it all when wind is good. If the U.S.
achieves 150 watts per person in 30 years it will be 10% of consumption, less
if transportation electrifies.

We are spending huge amounts of money to mass produce
uneconomic power systems in large numbers so that politicians can say they are
doing something. We should be spending that money on R&D to develop
technology that can make reliable, clean, safe, dispatchable energy cheaper
than burning coal. That technology will not need a massive grid or massive
energy storage to make electricity reliable.

Bill and Stephen, I can't believe you guys put so much effort into this discussion. The one thing that is clear: with today's limited interconnect of wind farms, utilities know that they must have 100% backup of all their wind power. The attempts to generate reliability and availability definitions are mostly just marketing and do not change this fact.

There is some benefit to linking the farms however. As Jacobson has shown, it can reduce the cost of transmission by providing a higher capacity factor. Also, it reduces the rate of change of wind power, so that less throttling will be required of the fossil fuel backup. This means that less of the backup must be fast-responding (but fuel wasting) simple gas turbines, and more can be combined cycle and coal.

Bill - "Compare the frequency of wind lulls in Ireland
with the frequency of gas line ruptures."

One last thing. Using graphs of this nature to demonstrate wind's variability has its problems as I have tried to explain to people like Peter Lang.

1. The windfarms are of greatly varying sizes. This means that large dips in the graph may be larger wind farms going in and out rather than complete lulls in the wind all over the country. ie: the wind might be blowing really strongly in an area where there are only a few small wind turbines.

2. You have no data concerning why the wind generation dipped. It may be that the output was curtailed due to oversupply rather than a wind lull. This is a graph of wind's contribution to the grid. You are assuming that dips are lulls in the wind however they also could be curtailed output and the wind might be blowing strongly.

3. Ireland is a pretty small island and is frequently covered by single weather events. It is 3 times smaller than our smallest mainland state (Victoria, Aust). Ireland will need multiple feeders to England to gain access to more dispersed wind.

"
A generating unit includes all equipment up to the high-voltage
terminal of the generator step-up transformer."

The definition of a
generating unit to me does not include the fuel supply from miles
away. If what you are saying is true then a maintenance strike in
another state affecting the gas supply to a unit is a reportable event
under the standard. The rupture of a high pressure line is simply a
mechanical failure well covered under the definition.

Again we are
not talking about the real world here only the strict interpretation of
the IEEE standard. In another instance:

"Reliability in this
standard encompasses measures of the ability of
generating units to perform their intended function."

Now if the
operator of a gas fuelled generating utility had performance penalties
tied to reliability and a gas line ruptured 1000km away then they would
claim that their unit was still able to perform it's intended function
and therefore its reliability was unchanged. So should the operator
here pay the penalty under the IEEE definition?

"The only way to
make wind farms that reliable is to
build a gas turbine or an enormous energy storage facility with each
farm,"

Now that is not even close to being true. Solar thermal
power plants can have an auxilary boiler and can acheive the IEEE
reliability standards however wind is another matter. It achieves a
measure of reliability by dispersion and connection. They also need a
small amount of gas generation to achieve the reliability that Jacobson
and others have calculated.

"Jacobson does not bend the standard, he writes his own
standard, and the reason for that is explained above."

Because as
you have seen above the standards, like any standards, need rewriting to
encompass all the new generating units coming on line now. It is a
process of continuous change that we all have to participate in.
Jacobson and others have shown that renewables well dispersed and
connected can provide a measure of reliability however that measure is
more statistical and empherical than shovelling in coal and churning out
power. The IEEE standards need to change with times and define the new
standards of renewable reliability so that renewable operators can
start to conform to these new standards and we will all be better off.

“Bill - First let me apologise for not picking up that you
had submitted a formal reply - I overlooked it. However it was not
accepted in the peer reviewed literature and you seem to claim that this means
that peer review is flawed and the internet is better. OK this also puts
you in very bad company.”

Stephen, perhaps you also missed the fact that they sent my
first round comment to publication twice without my permission.

The editor wrote;

“I have been informed by the authors of the original manuscript
that, after receiving your revised version of the Comments, they have no time,
nor are they interested in, revising their reply …. This leaves me no
choice but to go with the initial pair of Comments/Reply.”

The AMS procedure does not require an author response, it is
optional. In fact the AMS procedure specifies the author’s right to respond at
a later time.

The editor wrote;

“I recognize and appreciate the work that you have put into
the revision, but in the interest of moving the process forward and getting the
comments published, I have to accept the original Comments/Reply pair (April
2008).”

Here the editor acknowledges that the final comment, which
is essentially the first round comment with some additional points, is of high
quality, better than the one they tried to publish twice. They would not have
sent the final comment to the authors if it was not suitable for publication.
JAMC has never given a good reason for violating their published policy.

“The standard that you specified "IEEE Std. 762-2006,
“IEEE Standard Definitions for Use in Reporting Electric Generating Unit
Reliability, Availability, and Productivity." contains a hidded assumption
that you may or may not be aware of. The assumption is that the Generating
Unit is supplied with fuel”

“Hydro's fuel is gravity (with a working fluid of water) so
its fuel source is alway present. Winds Power's 'fuel' is the moving
working fluid of air so we have to assume for the purposes of assessing wind's
reliability under the standard that you referenced as always being there.

“Therefore these standards... all mention availability which
is a measure of the Generating Units ability to generate electricity if
supplied with fuel if you add the hidden assumption.”

Wrong, a fossil unit without a supply of fuel is not
available. To be available it must be able to generate power when called on to
do so.

“A wind farm in a lull is still available mechanically to
generate electricity so therefore this is not an outage either planned or
unplanned as defined by the IEEE.”

Not true. If a high pressure gas line supplying a gas fired
power plant running at 100% ruptures, the plant goes down, even if the rupture
was miles away and the plant is in pristine condition. That is a Class 1 forced
outage, the worst class. The same is true if a steam line ruptures supplying a geothermal
plant, or if a high pressure water line supplying a pumped storage plant ruptures,
or if a cloud passes over a solar farm, or if the wind at a wind farm lulls.

The problem with wind and solar is that the frequency of
cloud passings and wind lulls is vastly higher than gas line ruptures. If we
figure out how to put a solar farm in space it could be highly reliable if the
engineering is good enough. The only way to make wind farms that reliable is to
build a gas turbine or an enormous energy storage facility with each farm, and
when that cost is included, nuclear power plants will be very affordable by
comparison.

Compare the frequency of wind lulls in Ireland
with the frequency of gas line ruptures.

How much storage would Ireland
have to build to make wind baseload power?

“This is probably why Jacobson and others have to bend the
standards as they seem to apply more to conventional generators rather than the
new ones.”

Jacobson does not bend the standard, he writes his own
standard, and the reason for that is explained above.

It’s
all about keeping the grid up. When the grid goes down traffic lights go out,
elevators stop, factories shutdown, electric trains and subways stop. A lot of
productivity is lost and sometimes people die.

Grid managers
want to avoid causing huge financial losses and human deaths. They want to be
able to go home after work to enjoy their families and sleep comfortably.

That
is why they insist on real reliability standards like IEEE 762. Jacobson and
many others who are not responsible for actually keeping a grid up loose sight
of that fact.

"Specific findings and conclusions include the following:
• The LOLE analysis performed for EWITS shows that the existing
transmission network in the Eastern Interconnection contributes roughly
50,000 MW of capacity benefits. With the transmission overlays developed for
the EWITS wind scenarios, the benefit is increased by up to 8,500 MW.
• The LOLE analysis of the Eastern Interconnection with wind generation and
the transmission overlays shows that the ELCC of the wind
generation ranges from 24.1% to 32.8% of the rated installed capacity.
• The transmission overlays increase the ELCC of wind generation
anywhere from a few to almost 10 percentage points (e.g., 18% to 28%).
• The ELCC of wind generation can vary greatly by geographic region depending on which historical load and wind profiles are being studied. Although
interannual variations were observed, they are much smaller than those seen
in previous studies (see, for example, EnerNex
Corporation [2006]).
• Characteristics of the zonal ELCC differences among profiles tended to
be the same across all four scenarios."

They use much the same terminology as Jacobson:

"The fraction of the nameplate rating of a wind plant that can be counted as dependable or firm capacity, expressed as a percentage, is known as the capacity value."

And using the high resolution wind map:

"Assessing the capacity value of wind generation has been a staple of most of the integration studies conducted over the past several years. The approach taken in the EWITS project likely represents the most thorough and detailed investigation to date because of the size and scope of the model, the process by which area transfer limits were determined, and the sensitivities evaluated."

So two independant studies use much the same terminology and came to almost the same conclusion. That is the capacity factor of wind is greatly increased with transmission to widely dispersed wind farms and that capacity factor is roughly 30% of nameplate.

This of course is not reliability as I freely acknowledge and if you do merge the terms capacity factor and reliability wind is not as reliable as fossil fuels or nuclear. However Jacobson is correct that dispersing wind increases the capacity factor up to a level where integration into a electricity grid is far easier and causes far less problems.

As wind has the lowest marginal cost as detailed in this article by wind expert Jerome a Paris (incidently a great supporter of nuclear power) wind makes electricity cheaper and lower emissions:

"This tidbit of information, which will hopefully begin to contradict the
usual lies about the need for hefty subsidies for the wind sector, has
been publicised by EWEA, the European Wind Energy Association in a
report on the merit
order effect (PDF). This is the name for what happens when you
inject a lot of capital-intensive, low-marginal-cost supply into a
marginalist price-setting market mechanism with low short term demand
elasticity - or, in simpler words: when you have more wind, there is
less need to pay to burn more gas to provide the requisite additional
power at a given moment."

Bill - First let me apologise for not picking up that you had submitted a
formal reply - I overlooked it. However it was not accepted in the peer
reviewed literature and you seem to claim that this means that peer
review is flawed and the internet is better. OK this also puts you in
very bad company.

The standard that you specified "IEEE Std. 762-2006,
“IEEE Standard Definitions for Use in Reporting Electric Generating
Unit Reliability, Availability, and Productivity." contains a hidded
assumption that you may or may not be aware of. The assumption is that
the Generating Unit is supplied with fuel. Now this has great
implications for the literal interpretation of the standard as you are
insisting that Jacobson does.

Now if we define a generating unit
as a Wind Farm consisting of many wind turbines and that like the fossil
fuelled and nuclear generators it is supplied with fuel, then and only
then are you comparing apples to apples in the literal interpretation of
the standard. Hydro's fuel is gravity (with a working fluid of water)
so its fuel source is alway present. Winds Power's 'fuel' is the moving
working fluid of air so we have to assume for the purposes of assessing
wind's reliability under the standard that you referenced as always
being there.

Therefore these standards:

"3.22 Planned
Outage Factor (POF): The fraction of a given operating period in which a
generating unit is not available due to planned outages.

4.1.2.1
Planned outage: The planned outage state is where a unit is unavailable
due to inspection, testing, nuclear refueling, or overhaul. A planned
outage is scheduled well in advance.

3.26 Unplanned Outage Factor
(UOF): The fraction of period a generating unit is not available due to
unplanned outages.

4.1.2.2 Unplanned outage: The unplanned
outage state is where a unit is unavailable, but is not in the planned
outage state. (Unplanned outages are subdivided into maintenance outages
and forced outages)

4.1.2.2.2 Maintenance Outage: A maintenance
outage can be deferred beyond the end of the next weekend, but requires
that a unit be removed from the available state or another unplanned
outage state before the next planned outage.

6.11 Maintenance
outage hours (MOH) The phrase maintenance outage hours represents the
number of hours a unit was in a maintenance outage state.

3.14
Forced Outage Factor (FOF): The fraction of a given operating period in
which a generating unit is not available due to forced outages.

assume
that there is fuel and availability is independant of the fuel supply
with outages ONLY defined as mechanical failures.

A wind farm in a lull is still available mechanically
to generate electricity so therefore this is not an outage either
planned or unplanned as defined by the IEEE. Additionally by the
definition a wind farm has extremely good reliability as a wind farm
consists of many elements that can be maintained and fail without
affecting the availability of the wind farm as a whole. Therefore a generating unit of a wind farm will have far higher reliability than most fossil fuelled generators that consist of a single unit.

This is
probably why Jacobson and others have to bend the standards as they seem
to apply more to conventional generators rather than the new ones.

“Most scientists, quite rightly, do not engage in blog conversations as this
is not the proper forum for science. His refusal to comment shows
nothing. You are behaving like the climate change deniers that if a
climate scientist refuses to engage in public or blog debate then the science
must be wrong.

Submit a peer reviewed reply to the paper or give up critiquing it.”

Stephen, how did you miss the fact that I did exactly that? I submitted a
formal review comment to the Journal that published Jacobson’s paper. My
comment was peer reviewed and the reviewers did not find any technical errors.
They do not forward comments that are not suitable for publication to authors
for their response. Jacobson produced a very shallow response to the first
round comment and refused to respond to the more detailed final round comment.
What does that tell you?

“So how about posting some real science instead of blog posts.”

Stephen, you may have Jacobson and I mixed up. I am the electrical engineer
who used the industry standard for reliability defined in IEEE Std.
762-2006, “IEEE Standard Definitions for Use in Reporting Electric Generating
Unit Reliability, Availability, and Productivity.” I demonstrated that wind
is not a reliable source of power, not even widely dispersed interconnected
wind farms.

Jacobson is the civil engineer who made up his own definition of reliability
and refuses to talk about it, even in his chosen journal of publication.

Nathan - "I did not say that Jacobson intended to deceive; only that he did. I don't see how any reasonable person could read his paper and my critique and conclude that I was being dishonest. "

The only deception was your selective quoting. Jacobson clearly stated the limitations of the model in his list of assumptions. Your selective quoting missed the very important qualifications that are a part of every scientific paper.

I am sure you did not intend to be dishonest however selective quoting you did gave the impression that Jacobson used a daily average in order to make renewables more attractive. However the truth is that is he used it as a part of the model that he was using and clearly stated this.

Bill - "I would never engage Jacobson at his level. His refusal to
address the review comments shows that he is not interested in the truth
about
wind power reliability."

Then you have no right to question the work. Most scientists, quite rightly, do not engage in blog conversations as this is not the proper forum for science. His refusal to comment shows nothing. You are behaving like the climate change deniers that if a climate scientist refuses to engage in public or blog debate then the science must be wrong.

Submit a peer reviewed reply to the paper or give up critiquing it.

Actually it demonstrates the nature of the pro nuclear argument pretty well. Nothing so far has been posted from peer review that shows nuclear is essential to the future energy mix. The only people doing real research seem to be renewable people.

Nathan - "My central complaint is that there is a large gap between
what most environmentalist believe renewables can
achieve (nearly 100% of our electricity), and what utility industry
insiders and NREL researchers believe is economically feasible
(20-30%)"

Economically feasible and technically feasible are two completely different things. Industry insiders are usually bound by what they have at the moment and are usually extremely reluctant to change.

Additionally the research that Jacobson and others are doing is pointing the way toward a 100% renewable future. The papers are NOT quasi-technical as they are at least peer reviewed. So if you have a problem with the peer review process then you are in very bad company.

"Even the Sci-Am Solar Grand Plan by Zweibel, Mason, and Fthenakis of
2008"

I am sure they do however Diesendorf shows that large scale storage is not needed for wind. Well dispersed wind only only needs extra peaking backup that is seldom used which Jacobson confirms with his studies. All these studies are based on a set of assumptions - what the truth is we will only know when these things are put into practice. I freely admit that the work on the actual performance of wind in Europe is a worry and points to a discrepancy between calculated performance and actual. However it seems that the subsidies in some countries has distorted the figures. Spain probably will tell the best story over the next few years and I will be very interested to see what the final figures from Spain will be like.

Stephen. “So write your own peer reviewed paper in response and
engage Jacobson at his level.”

I would never engage Jacobson at his level. His refusal to
address the review comments shows that he is not interested in the truth about
wind power reliability.

Scientists understand that to advance science we must follow
the truth wherever it leads by asking and answering tough questions. His
refusal to address the points raised in the review comment shows that he is not
a true scientist or engineer; he is a wind power activist posing as an
engineer.

“For every paper
there will be objections and your objections also involve assumptions and can
be questioned.”

The difference is that I respond to questions about my position.
I invited Jacobson to discuss his paper in a multi round conversation similar
to the one with Dr. Sovacool. Jacobson, and you do not answer questions that
explore the logic underlying your position, as indicated by your final comment
on this story.

Stephen, "By selectively quoting you are creating the impression that Jaconson intends to decieve which is a very serious charge."

My central complaint is that there is a large gap between what most environmentalist believe renewables can achieve (nearly 100% of our electricity), and what utility industry insiders and NREL researchers believe is economically feasible (20-30%). I'm suggesting that a possible reason for this gap is that a few quasi-technical papers have created false hope by making claims of very high renewable penetration that are not supported by rigorous science. The Jacobson paper is a good example, so I'll remind you of his abstract:

"...We conclude that combining at least four renewables, wind, solar, geothermal, and hydroelectric power in optimal proportions would allow California to meet up to 100% of its future hourly electric power demand assuming an expanded and improved transmission grid."

Even the Sci-Am Solar Grand Plan by Zweibel, Mason, and Fthenakis of 2008 admitted the need for very large scale energy storage, and ascribed only a very small roll for wind power and roof-top solar in non-desert regions of the country (the favorite technologies of most environmentalists), presumably because of their poor compatibility with known storage technologies. This important reality was not mentioned by Jacobson (beyond the existing hydro).

In another paper which conflicts with Jacobson, Diesendorf (http://wwf.org.au/publications/clean_energy_future_report.pdf, 2004) has advocated scenarios in which wind power is kept to 20% penetrations and diluted with large amounts of natural gas and dispatchable bio-fuel consumption; he also speculates about the benefits of future breakthroughs in energy storage.

I did not say that Jacobson intended to deceive; only that he did. I don't see how any reasonable person could read his paper and my critique and conclude that I was being dishonest.

Wilmot - " So Diesendorf does not contradict the 20% limitation
on wind integration. In fact, he supports the expert consensus that
wind will not be able to do the job now done by coal and nuclear. "

He does no such thing. At 20% wind can be incorporated with the normal operational reserves of a conventional grid. After 20% you need the extra balancing peaking power that Diesendorf mentions to equate well dispersed wind with baseload power plants.

The papers on wind's capacity factors I posted show nothing more than a lot of wind in Europe is in sub optimal sites which is a consequence of the feed in tarrifs that are unique to Europe. In the USA and Australia wind is far more likely to be installed in good wind regimes which boosts the CF.

On page 5 are the listed measured CFs. Countries like the UK, Ireland and Greece all have high CFs. Countries like Germany (18.3) have the lowest which drags down the average. The point is the the puzzle of why measured wind CFs do not stand up to the calculated CF is that a subsidy regime has caused a lot of sub optimum wind to be built which is bad for wind as this figure is used by people rather than analysing the figures like the author did and explain why this is the case.

Wind farms place in good wind regimes can have CFs up to 30% which is right in the range which Diesendorf and Jacobson assume them to be.

Additionally conventional nuclear power cannot be used as a backup for wind power as it is non-despatchable. If you want despatchable nuclear you will need to somehow build load following plants like in France.

Nathan Wilson - "The result is energy equivocation: the words may be true individually,
but the overall conclusion is completely false.
Jacobson has created another tool to mislead the casual reader and the
optimistic environmentalist."

By selectively quoting you are creating the impression that Jaconson intends to decieve which is a very serious charge. This is the entire quote:

"Assumption 3: Our analysis is performed only for the average day in each month. By averaging demands, wind speeds, and insolations over the month, we are removing much of the fine variability in output that worries grid operators the most. Our model shows that the complementary intermittencies of wind and solar and the balancing power of hydro can deliver a relatively smooth, peaking supply despite seasonal and perhaps even day to day variations in supply. But our model does not address the issue of hour to hour or sub-hour fluctuations in wind or solar output. To a large extent these will be dampened due to the combination of huge, widely distributed capacities over the state, but they will not be removed entirely. A good follow-up to this model would be to use modeled or measured wind speeds and insolations on several specific days, with as good temporal resolution as possible, to calculate the statewide power supply from this same resource mix. This could reveal the utility of the average as a forecasting tool, as well as the range of variability present in a real system."

(My bold characters) If you had of quoted the entire text you would see that Jacobson clearly states the limitations of the model and further reading would show that he proposes changes to get a better model.

Selectively quoting to suit you own argument is simply dishonest. If your argument is so weak that you need to resort to such tactics then our conversation is at an end.

A guest says:

Perhaps the issue could be advanced by isolating a significant grid and powering it with solar and wind, combined with a smart grid. I would suggest selecting the nation's capital as the test bed, including all of the federal buildings in the District of Comedy. Once our elected representatives had experienced a year of reliable, reduced cost operation of this test bed, I believe we would be ready for a broader rollout. :-)

Stephen, I did read the Diesendorf 6-page paper (not peer-reviewed)
entitled "The
Base-Load Fallacy." This dates from 2007 so I suppose it reflects
his thinking since the previous articles which were string-cited at the
end of your quote, which I did not look up. He lists 8 points which,
considered together, state the case for a sufficiently large
"renewables" capacity to be considered an adequately reliable substitute
for conventional sources, such as coal and nuclear. Point 1 is that no
system is 100% reliable. So? Does it follow that since no system is
perfect, all systems are equal? Point 2 is that present systems already
incorporate a mix of baseload and peak power from various sources. Of
course. Point 3 is where you and I differ, with respect to solar
thermal being considered baseload despite its wimpy capacity factor.
Unlike geothermal, solar thermal needs to be supplemented with gas for
when insolation fails, such as at night and in winter. Point 4 is that
wind and solar without thermal storage "have different kinds of
variability from coal-fired power stations and so have to be considered
separately" -- of course. Points 5 through 8 state the case for wind to
be considered as baseload capacity, despite its small capacity factor,
if it is widely enough distributed and has adequate backup. You have
corrected the assumption of wind capacity factor from 35% to 21% in
light of recent European experience, so maybe this would have some
effect on Diesendorf's argument, but the point is moot because in Point 8
Diesendorf concludes: "As the penetration of wind power increases
substantially, so do the additional costs of reserve plant and fuel used
for balancing wind power variations. However, when wind power supplies
up to 20% of electricity generation, these additional costs are still
relatively small." So Diesendorf does not contradict the 20% limitation
on wind integration. In fact, he supports the expert consensus that
wind will not be able to do the job now done by coal and nuclear. So
you see why I failed to find the refutation you expected me to find
there. I find more persuasive Nathan Wilson's analysis, and continue to
maintain that the Emperor has no clothes.

Jim brings up an interesting point: "...all the costs associated with decommissioning nuclear plants and returning the site to greenfield, and all costs associated with waste management and disposal are fully included in the (present day) cost of nuclear electricity."

Perhaps we should instead only plan to return nuclear sites to brownfield status. I think our decendants will build new nuclear plants on the same sites as our plants. No one seriously contemplates returning an old city to greenfield status, we just assume we'll need that space to hold future people. In the same way, we'll need space for future power plants too.

Bill, good comments, however, "windfarms that need to be backed up by conventional plants", is actually too weak (all generator need some backup).

Due to the low capacity factor (30-42% in the US and <25% in Europe), strong correlation between distant sites, and anti-correlation with demand, wind energy actually needs to be diluted 3:1 with dispatchable power. This is an extremely important but widely misunderstood fact of the wind industry.

In other words, wind can help us to begin reducing our fossil fuel consumption in the beginning, but later on, it will be come a barrier to further reductions!

In the paper, he claims to have devised electrical portfolios to produce 80% and 100% of California’s 2020 electrical demand using renewables. Even in the 80% case, the remaining 20% is not peaking power to fill-in for renewable variability as one might think; it is “conventional baseload”.

This quote is from page 17: “Assumption 3: Our analysis is performed only for the average day in each month. By averaging demands, wind speeds, and insolations over the month, we are removing much of the fine variability in output that worries grid operators the most.”

The result is energy equivocation: the words may be true individually, but the overall conclusion is completely false. Jacobson has created another tool to mislead the casual reader and the optimistic environmentalist.

Regarding the EWIT study wind data. Yes it is modeled, but the model data is fitted to real-world measurements from dozens of sensors gathering hourly data for the 3 year study period. Nothing this complete was available to Diesendorf when he wrote his papers in the 1980s or 1990s.

From EWITS page 66: “The project that produced these data modeled the atmosphere over the study area using mesoscale modeling tools. Mesoscale refers to atmospheric phenomena (temperature, pressure, precipitation, and wind, for example) on scales of several kilometers to several hundred kilometers. By using known meteorological measurement data for historical years, the model can be guided to reproduce what the wind speeds and air density would have been at many points, both on the ground and at wind turbine hub height. Those wind speeds are used, along with local geographic information (e.g., mountains, lakes, and ridgelines), to estimate an area’s wind power production over the time frame of the numerical weather simulation.”

Stephen, you keep making the point that aggregation of wind sites reduces the variability; of course I agree. But the effect is so weak that even with large systems covering areas such as the eastern half of the US, the bottom is still that dispatchable power must supply the remaining 70-80%. This is a common understanding in the utility industry, and to date there has not been a good study that contradicts this. This is in spite of the fact that many researchers such as Jacobson have clearly been trying and failing.

Here is a quote from a paper based on real data that shows
how the incorporation of wind power sometimes INCREASES harmful emissions.

“Not only does wind
generation not allow ERCOT utilities to save SO2, NOX and CO2 emissions, it is directly responsible for creating
more SO2 and NOX emissions and CO2 emission savings are minimal at best.”

I made several responding comments beginning with the one on
at 02:42 PM on 03/15/10.

People like to compare conventionally powered grids with
conventional grids combined with windfarms and show that a little less fuel is
burned. But the correct comparison would be a grid in which the same amount of
money spent on the windfarms, was spent on reliable energy sources such as
geothermal, nuclear, solar with massive storage or wind with massive storage.

If wind and solar farms had to include the cost of transmission
lines, backup power, voltage and frequency regulation in their cost estimates, I
think fission would become the preferred low emission energy source. We are
wasting a lot of money on windfarms that need to be backed up by conventional
plants.

I posted the paper on Wind Capacity factors however the conclusion is this as obviously you did not read it nor the other papers that I posted:

"The fact that WPG happens to be less efficient than previously thought is no reason
for society to withdraw its support since WPG remains the unique RES able to expand on
a large scale at a reasonable cost to meet committed RES targets (and carbon emission
reduction).38 Moreover, new technologies such as solar thermal, solar photovoltaic, tidal,
wave power or even fuel cells in conjunction with the formers are emerging and may
someday become as competitive as WPG to meet our environmental goals. Tracking the
progress (or lack thereof) in each field for institutional support is thus essential to avoid
policy being trapped into a sub-optimal renewable technology."

Bill Woods - "Seriously, it's very odd for such a big fan of solar power to arguing
that, "We need to all co-operate on a new lower energy way of
life.""

And if we could directly use solar energy then this would be true. However the solar energy to electricity converters take resources to build. Attempting to provide converters to all the worlds population at the rate Americans and Australian's use energy I believe would be almost impossible. Us reducing our energy use and embracing the term sufficiency would ease the drain on the Earths resources which are limited.

Nathan Wilson - "I should note that Mark Jacobson has used this data in a
recent paper
claiming that California could get most of its electricity from
renewables. However, he clearly admits that he averaged out the daily
variations by using monthly averages instead. We can all draw our own
conclusion as to why he did this."

You will have to provided a link
and a quote from that paper because I can find no such statement in the
papers that I can find.

"Hourly
and daily averaged wind speed measurements were available from surface
stations at a standard elevation of 10 m above the ground (V10
hereinafter). Observed vertical profiles of wind speed were available at
sounding stations, generally 2 times per day (0000 and 1200 UTC).

and
the conclusion from this paper is:

"In conclusion, this study
implies that if interconnected wind is used on a large scale, a third or
more of its energy can be used for reliable electric power and the
remaining intermittent portion can be used for transportation (i.e., to
power batteries or to produce hydrogen), allowing wind to solve energy,
climate, and air pollution problems simultaneously."

"In order to estimate winds offshore,where little in-situ data
exist, the Penn State/National Center for Atmospheric Research Mesoscale
Model version 5 (MM5)weathermodel [23]was run over the offshore parts
of CA found suitable for turbine development in the previous section.
The decision to use MM5 instead of in-situ data and/or satellite wind
fields was based on the high spatial and temporal resolution wind fields
that meso scale modeling would provide"

The only reference to
monthly data is this:

"To reduce the amount of computer time
needed for a climatologically significant wind resource study four
seasonal months (Jan, Apr,Jul, and Oct) were modeled for two of the
model years used in the study(2005and2006) instead of the
entire12months. It was assumed that n80 m of the four seasonal months
approximated the n80 m of the
entire 12 months of that year."

The
reason is clearly stated and the error estimated from this assumption.

Nathan Wilson - "NREL has recently released a very detailed study of wind power on the
eastern half of the US, which used real sub-hourly data for wind power
and a real grid simulation with thermal power plants and new
transmission lines."

"A precursor to EWITS known as the Eastern Wind Data Study (AWS Truewind 2009) identified more than 700 GW of potential future wind plant sites for the eastern United States. All the major analytical elements of EWITS relied on the time series wind
generation production data synthesized in this earlier effort. The data cover three historical years—2004, 2005, and 2006—at high spatial (2-kilometer [km]) and temporal (10-minute) resolution. On- and offshore resources are included, along with wind
resources for all states."

Now I am not discounting computer models however it is not real world data as you seem to indicate. The study as far as I can see makes no mention of a limit to wind penetration. The studies were for very specific penetrations of 20% and 30%.

This quote from page 13:

"Transmission helps reduce the impacts of the variability of the wind, which reduces wind integration costs, increases reliability of the electrical grid, and helps make more efficient use of the available generation resources. Although costs for aggressive expansions of the existing grid are significant, they make up a relatively small portion of the total
annualized costs in any of the scenarios studied."

is almost exactly what Diesendorf and others are saying. Dispersing wind and connecting it up increases the reliability.

For two decades, the capacity factor of wind power measuring the mean energy delivered by wind turbines has been assumed at 35% of the name plate capacity. Yet, the mean realized value for Europe over the last five years is closer to 21% thus making levelized cost 66% higher than previously thought. We document this discrepancy and offer rationalizations, emphasizing the long term variations of wind speeds. We conclude with the consequences of the capacity factor miscalculation and some policy recommendations.

Does not seem to be a rabidly anti wind however it brings up some valid points.

Nathan Wilson -"So you believe there is (or will soon be) too much energy demand
(perhaps from too many people)? "

Of course I do - what other conclusion is there? The classic question is for a group of bacteria doubling every minute in a bottle that will be full at 12:00 what timeis it when is the bottle is half empty? You should be able to answer this without any calculation if you understand the exponential function. The other part of this is if the bacteria found another 3 bottles of the same size and expanded the living space by 3 times how long would it take to fill the other 3 bottles?

"E.g. if I can afford a Tesla Roadster or a Nissan Leaf, why should I
take the bus?"

However you can only do this if 100 or more people or more cannot do it. Do you think that all 1 billion and 800 million Chinese and Indian people can also do this?

The question really is "why should I use a highly expensive individual transport system when the bus is perfectly adequate". Not that I do not mind you - I am as bad as anyone however moving forward we need to perhaps embrace the concept of sufficiency.

It is a philisophical question that probably has no place in an energy discussion however that is more and more where I am going lately - thinking about the actual ethics of continual and unrestrained growth.

Stephen, do you have a link for the Diesendorf paper you quoted? I'd like to see if this one is any better than the others I have read. They were obsolete and wrong.

His work from the 1980s in which he claimed that aggregated wind farms could supply baseload was based on assumptions about the wind variability and correlations at different locations.

For the US, the DOE's NREL has made real-world measurements at many sites across the country over a period of a few years. It is inexcusable to ignore this recent data when making claims regarding the reliability of wind power.

I should note that Mark Jacobson has used this data in a recent paper claiming that California could get most of its electricity from renewables. However, he clearly admits that he averaged out the daily variations by using monthly averages instead. We can all draw our own conclusion as to why he did this.

NREL has recently released a very detailed study of wind power on the eastern half of the US, which used real sub-hourly data for wind power and a real grid simulation with thermal power plants and new transmission lines.

What this study says is that due to the variability of wind, and correlation among even widely distributed farms, a system with 20% wind is feasible, and 30% is only barely doable and is significantly more expensive. So you will not convince me otherwise unless you can produce an equally detailed study, and show where the NREL went wrong.

You've said previously that adding other variable renewable source will solve the variability problem. NREL is working on a similar study for the western US, which includes solar. Until that study is complete, I'll consider it unlikely that the result will be much different than the EWITS result. And I'll continue to maintain that the best science and engineering we have today says that nuclear power can economically provide 70-90% of our electricity, but renewables can only provide 20-30% (see France and Denmark for examples of these numbers).

One more thing: your plan to focus first on efficiency and use nuclear power as a last resort (like Lovins' failed "Negawatts" plan) will certainly serve to prolong the fossil fuel era. Efficiency can only be used with an energy source, not by itself (obviously).

Stephen, we are starting to get down to the core of the issue I think: "...I realise that you are an exponential function denier and think that we can continue growing for ever and ever...."

So you believe there is (or will soon be) too much energy demand (perhaps from too many people)? I can understand why a person would come to this conclusion if he or she believed that fossil fuels or hydro power were the only energy sources available. Or if they didn't like humanity itself.

It's now widely believed that we are not on a path toward infinite population. Developed countries are mostly suffering from insufficient birthrate to replace ourselves. That could eventually be a world-wide problem.

It's now established fact that the Earth has more energy available than we can possibly use (economically), for the life of the planet, from two sources: solar energy and nuclear power via breeder reactors. I've seen comments from you in the past in which you dispute the feasibility of breeder reactors (I don't agree with you), but I've not seen you dispute solar. So I do not know of any scientific reason why we should not allow people to have as much energy as they want and can afford. E.g. if I can afford a Tesla Roadster or a Nissan Leaf, why should I take the bus?

By way of disclosure, I should also admit that I am pro-space travel. Space travel is the most energy intensive thing humans do, and doesn't make any sense on an energy constrained world. As Carl Sagan Larry Niven [thanks Bill] used to say, the dinosaurs are extinct today because they didn't have a space program. I don't believe humans should follow that example. The solar system is chock-full of natural resources, all waiting to be exploited by energy-rich people from planet Earth.

The utility must generally supply some minimum power level or base load 24 hours per day every day of the year. Industrial plants, hospitals, and even residential customers with their refrigerators all contribute to this base load.

The generating plants that are the most economical to operate are used to supply this base load. These base load plants are usually large steam generating plants that cannot be started and stopped quickly. Since these are some of the least costly plants to operate, they are usually loaded or dispatched close to their maximum power level."

Geothermal and solar thermal with supplemental fuel are despatchable and can supply the minimum power levels required. However they can do more that this as they can economically load follow as well.

Studies done by Mark Diesendorf and others show that wind can replace baseload power plants:

"Computer simulations and modelling show that the integration of wind power into an electricity grid changes the optimal mix of conventional base-load and peak-load power stations. Wind power replaces base-load with the same annual average power output. However, to maintain the reliability of the generating system at the same level as before the substitution, some additional peak-load plant may be needed. This back-up does not have to have the same capacity as the group of wind farms. For widely dispersed wind farms, the back-up capacity only has to be one fifth to one-third of the wind capacity. In the special case when all the wind power is concentrated at a single site, the required back-up is about half the wind capacity. (Martin &Diesendorf 1982; Grubb 1988a & b; ILEX 2002; Carbon Trust & DTI 2004; Dale et al. 2004;UKERC 2006)."

References are at the bottom of the quote if you would like to look them up. You might also want to read the "Baseload Fallacy" written by Mark that explains how the grid works and what the different power station do.

Stephen, "same old tired argument, refuted at every turn" is a crushing
rebuke. Please accept my assurance that I am not intentionally
repeating something I know is wrong, and that I am not aware of the
(presumably published) refutations you mention. Where are they? You're
not just trying to shout me down, are you? As for the Hair Shirt
argument, I guess you and I will continue to courteously disagree on
whether Hair Shirts are comfortable or not.